Exemplary embodiments of the present invention relate generally to system and methods for providing material to a gasifier. Exemplary embodiments also relate to an outlet tube for an extrusion system. Embodiments of the outlet tube may, for example, be used to deliver material to a gasifier or may be used for other non-gasifier purposes. Further embodiments relate to an isolation gate that may be used in a material delivery system or may have other purposes.
A gasifier is a system that uses intense heat, substantially without combustion, to convert a solid material to gases. One example of a gasifier is a plasma furnace that uses a high-temperature arc to facilitate the conversion. Other examples of gasifiers include: counter-current fixed bed, co-current fixed bed, fluidized bed, entrained flow, and free radical. It is not intended to limit the invention to any particular type of gasifier unless expressly set forth otherwise.
Gasification is becoming increasingly more in demand. The process may be an effective means to dispose of waste materials including, but not limited to, municipal solid waste (MSW). Other types of feedstock may also be used in a gasifier such as organic materials, fossil-based carbonaceous materials (e.g., coal and petroleum coke), and biomass materials and other waste-derived feedstocks (e.g., wood, plastics, aluminum, refuse-derived fuel (RDF), agricultural and industrial wastes, sewage sludge, switchgrass, various crop residues, and black liquor. Other types of feedstock are possible. Accordingly, it is not intended to limit the invention to use with a particular feedstock unless expressly set forth otherwise.
Gasification may also result in the production of useful products. The produced gases, which commonly include hydrogen, carbon dioxide, and carbon monoxide, may be referred to as syngas (i.e., synthetic gas), and it may be used as a fuel or in the production of other energy sources (e.g., other synthetic fuels). Syngas may also be used to produce synthetic chemicals or other types of energy such as heat, electricity, and power. In addition to syngas, a typical gasification process may also produce some slag material. However, even this slag material may serve beneficial purposes (e.g., reuse in pavement materials).
A drawback, however, exists with respect to the known systems and methods for providing material to the gasifier. Because of the intense heat, care must be taken to contain the heat. Typically, a batch delivery system and method is used to deliver the waste material to the gasifier, which may be comprised of multiple distinct devices to advance the material in batches. With such a system, a mechanical airlock is used to seal the gasifier with each load. However, airflow to the gasifier is only marginally controlled, as there is still free air within the airlock chamber along with feedstock which can cause combustion of the material and can make control difficult. Moreover, known batch delivery systems and methods limit the amount of material that can be delivered to the gasifier. Furthermore, because of the characteristics of the batch feed supply, the material is burned in an uneven and irregular pattern, which can impact the conversion to gas. A need, therefore, exists for an improved system and method for processing material for a gasifier. A need also exists for a system and method adapted to extrude material in a manner that overcomes the disadvantages of batch delivery. In addition, a need exists for a system and method of isolating an area or a flow of material. Furthermore, a need exists for a system and method for creating a substantially airtight seal with a flow of a continuous plug of material to a gasifier.
Exemplary embodiments of the present invention may satisfy some or all of the aforementioned needs. For instance, one exemplary embodiment may deliver a flow of a feedstock material to a gasifier such that the flow of the feedstock provides a substantially airtight seal to the gasifier. Another exemplary embodiment provides a tube for an extrusion system that is adapted to allow a desired flow of material through the tube. In one example of the tube, it may be adapted to provide material to a gasifier, but other examples may have other uses. Another embodiment is directed to a system and method for providing material to a gasifier with an auger. Yet another embodiment relates to an isolation gate such as for isolating an area or a flow of material. Still other embodiments may combine some or all of the features of the aforementioned embodiments. As such, exemplary embodiments may overcome some or all of the previously described disadvantages of the known art. Nevertheless, it should also be recognized that some of these exemplary embodiments may have utility in other areas unrelated to gasification.
In addition to the novel features and advantages mentioned above, other benefits will be readily apparent from the following descriptions of the drawings and exemplary embodiments.